The laboratory of the Principal Investigator of this Core has recently developed the aRNA amplification procedure and expression profiling technique for the analysis of coordinated changes in gene expression from tissue samples as small as a single cell. The need for single cell analysis of gene expression is necessitated because of the cellular heterogeneity and complexity of the brain. With the additional heterogeneous nature of traumatic brain injury (TBI), the potential utility of the examination and quantitation of gene expression in specific models of Diffuse vs. Focal vs. Mixed brain injury becomes even more powerful. This Core will provide single cell aRNA amplification and expression profiling technology as a service to the following projects: With Project 2, we will evaluate the pattern of gene expression in individually injured cells from the mouse CCI (focal injury) model in wild-type, neurofilament knockout or transgenic mice. Together with Project 3, we will employ single-cell aRNA amplification on individual cells obtained from mouse CCI (Focal injury), rat fluid-percussion (mixed injury) models as well as human tissue (from the Glasgow Core via specific aim 4 of Project 3). Finally, in conjunction with Project 5, we will use the information in single-ell expression (Transcript-Aided Drug Design or TADD) which will be performed as specific aim 3 of Project 5. Gene expression profile information will be shared across projects. It is hoped that this core will permit the detailed analysis of the mRNA changes associated with injured cells as they progress to cell death and lead to novel therapeutic interventions for TBI.